Portable refrigerator



FIG. 1 is a perspective view of a first embodiment of a portable refrigerator, showing my new design in a closed door position;

FIG. 2 is a another perspective view thereof, shown in an open door position;

FIG. 3 is a perspective view of a second embodiment of a portable refrigerator, showing my new design in a closed door position; and,

FIG. 4 is another perspective view thereof, shown in an open door position. 

CLAIM We claim the ornamental design for a portable refrigerator, as shown and described. 